On 14/04/11 10:37 AM, "Yong Zhang" <2010202...@njau.edu.cn> wrote:
> Dear all, > > I conducted the two-way indicator species analysis using TWINSPAN program, and > following is the final result: > > 000000000000000000000111 > 000000000001111111111011 > 011111111110000000111 > 01111111110000001001 > > I have to certify my analysis, I want to classify the above 24 sampling sites > into 3 major groups based on 7 biotic metrics. The name of my 24 samples could > be site1 to site24, from the left to the right, and I set the cut levels 0, 2, > 5, 10, 20, the maximum level of divisions: 6, and maximum group size for > division:3 . > > Now, my question is whether my setting is correct? And how should I classify > these sites into 3 groups accoding to this final result? Dear Yong Zhang, This is not an R issue, because there is no TWINSPAN in R. However, the answer to your question is that strictly speaking you cannot group your data into three major groups with TWINSPAN. TWINSPAN is a bisection method so that first division gives you two groups, and second splits each of these into two groups so that the next choice is to have four groups. However, in this case one of the groups was so small (3 plots were split off from other in the first division, and then these were split into groups of 2 plots and 1 plot) that you probably can ignore the second division of the small group. If your goal was as vague as wanting to classify 24 sites into 3 major groups you could do better than use TWINSPAN: what's the problem with proper classification methods in R? Moreover, have you checked that your "biotic metrics" suit to the pseudospecies cut level concept of TWINSPAN? Cheers, jari oksanen _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
